Add another to the list of Democratic victims of ObamaCare:

Democratic Sen. Ben Nelson of Nebraska will announce today that he is retiring after two terms, a serious blow to Democratic efforts to hold onto their majority in the chamber next November.

Nelson is scheduled to hold a press conference back home in Nebraska as early as today to make his decision official, said several Democratic insiders close to the leadership. …

The White House and top Senate Democrats, including Majority Leader Harry Reid (Nev.) and Sen. Chuck Schumer (N.Y.), had quietly mounted a pressure campaign to keep Nelson from retiring. Nelson has more than $3 million in his campaign war chest, and his approval rating solidified after falling over the last several years.

But with Nelson stepping down, the Democrats’ hold on the Senate is in serious doubt, although Democratic leaders believe they can still do so. Republicans are expected to pick up control of the Cornhusker State seat, although popular former Sen. Bob Kerrey (D) has been talking to top Democrats about possibly running again.

How big of a deal is this?  On one hand, it’s easy to underestimate the power of incumbency.  On the other, the man couldn’t even eat a pizza in peace after casting a decisive vote for ObamaCare and tossing his pro-life credentials into the wastebasket by doing so.  Nelson wasn’t going to get re-elected, and would likely have lost by a wide margin in a very red state, especially in a presidential election cycle.

Democrats could try to get Kerrey to return to Nebraska, but getting him elected will be a tall order.  He was a popular Democrat, but he’s spent most of his time out of Congress in New York as president of the progressive New School.  He retired from that position at the end of last year, but had previously toyed with returning to politics — as mayor of New York City.  That doesn’t seem to be a good resume for a Senate campaign in Nebraska, even if Kerrey defied the New School faculty and endorsed the invasion of Iraq in 2003.

I don’t think Nelson’s retirement really changes the calculus in Nebraska.  In a presidential cycle, a credible Republican candidate will be almost certain to replace Nelson, even if Nelson is no longer running.

Update: The Omaha World-Herald confirms Nelson’s decision to retire, and points out the political layout in Nebraska:

Democrats have no candidate waiting in the wings. They will have to scramble for a candidate who can quickly organize a statewide campaign and raise millions in less than a year, while competing against Republicans who have been in campaign mode for more than a year.

It’s not impossible, but the odds are long. Some Democrats whose names have been bandied about as possible contenders include State Sen. Steve Lathrop and former Lt. Gov. Kim Robak.

For Republicans, the dream of holding all five of Nebraska’s congressional seats and all five statewide offices is now within reach.

Nelson was the lone Democrat to hold a high statewide or federal office in Nebraska. The next highest-ranking Democrat in the state is Omaha Mayor Jim Suttle.

There’s a reason for that shutout in federal offices; Nebraska went for John McCain in 2008 by 15 points and nearly 140,000 votes in a race that Obama won by seven points nationally.  After ObamaCare and the betrayal of Nebraskans by supposedly conservative Democrat Ben Nelson, it’s very likely that it will take a long time for Nebraskans to trust a Democrat to be conservative and pro-life in Washington again.